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Comparative foliar micro-morphological characters of the species of portulacaceae in Nigeria.

INTRODUCTION

Portulacaceae is a medium-sized family of annual or perennial, more or less succulent herbs or sub-shrubs. The family is cosmopolitan and it is more centred in South Africa and America. It has 19 genera and 500 species across the world (Heywood,1978). In Nigeria, only 2 genera and 6 species are present (Hutchinson and Dalziel, 1954). The species in the family have both medicinal and nutritional values and these species are Talinum triangulare (Jacq.) Willd., T. cuneifolium (Willd.) DC, Portulaca oleracea Linn., P. foliosa Ker-Gawl, P. grandiflora Hook. and P. quadrifida Linn. Portulaca oleracea is used for treating swellings, bruises, ear-ache, tooth-ache and to control palpitation and other cardiovascular diseases (Evans, 1996; Dalziel, 1937). Members of the family are also used as vegetables, potherb and salad.

The taxonomic treatments of the family have elucidated the importance of both morphological and anatomical characters in the recognition of the species (Hutchinson and Dalziel, 1954; Nyananyo and Olowokudejo, 1986). However, there is insufficient information on microscopic characters of the members of the family which can easily aid their recognition. Apart from this, the opinion of Heywood, (1978), that some genera of the family are ill-defined and that they can be distinguished from one another by microscopic features also encouraged the present study. In addition, the need to contribute more data to enhance understanding of the taxonomy of the family is another reason for the study. The use of foliar epidermal characters in distinguishing species and genera has been reported by workers (Fontenelle, et al, 1994; Kadiri and Ayodele 2003; Nyananyo and Olowokudejo, 1986; Ogundipe and Adegbite,1991, Ogundipe and Wujek, 2004; Singh and Dube, 1993). In the present study, both quantitative and qualitative micro-characters of the leaves of the six species of the family occurring in Nigeria are presented to elucidate their differences and similarities.

MATERIALS AND METHOD

Cuticular preparations

Both fresh and dried materials were used for the study using the methods of Kadiri and Ayodele (2003), Ogundipe and Adegbite (1991), Ogundipe and Wujek, (2004). 5cm x 5cm leaf portions were taken from standard median portions of the leaf lamina. Dried leaf material was swelled in boiling water for 30-60 minutes and then soaked in trioxonitrate (v) acid for about 6-18 hours until air bubbles were formed on the leaf material. Leaf epidermides were separated and cleaned of tissue debris with a pair of forceps and fine hair brush. The epidermides were mounted with upper surfaces uppermost on glass slides and few drops of ethyl-alcohol were added in series: 50%, 70%, 90% and 100%, then up to 5 drops of Safranin O were added. Excess stain was washed off in water and one drop of glycerin was added and then covered with cover slips and the edges ringed with nail varnish to prevent dehydration and preparations were observed at x400. Drawings presented in Fig. 1 were made using M12 WILD microscope fitted with camera lucida drawing apparatus. List of materials used for the study is presented in Table 3.

RESULT AND DISCUSSION

The leaves are generally amphistomatic, with more stomata present on the abaxial surface. Stomata are usually paracytic on the abaxial surface whereas they are hemi-paracytic to paracytic on the adaxial surface of all the species. (Fig.1a-1, Table 1).

Nyananyo and Olowokudejo (1986) reported parallelocytic in Talinum while Metcalfe and Chalk (1950, 1979) documented only paracytic for the family. Cell shape is usually irregular in all species except Portulaca grandiflora Hook that is isodiametric on the adaxial surface and irregular on the abaxial surface. Anticlinal wall pattern is either identical on both surfaces or dissimilar on either surface, it varies from straight-curved in all species (Table 1, Fig. 1) except T. triangulare, T. cuneifolium and P. quadrifida that have undulate pattern. (Table 1, Fig. 1a-d, g,h).

In Talinum, mean stomata distribution is uniform on both surfaces of T. triangulare, whereas it is more on the surfaces of other species. Stomata are usually larger on the abaxial surface than adaxial surface in all the species and mean size varies from 13.0 x 4.5[micro]m-20.5 x 5.5[micro]m on the abaxial surface to 20.0 x 4.0[micro]m-26.5 x 7.5[micro]m on the adaxial surface.(Table 2). There are more epidermal cells on the adaxial surface than abaxial surface in all species except T. triangulare. On both abaxial and adaxial surfaces, mean cell size ranges from 63.0-120[micro]m x 20.5-51.0[micro]m and 80.0-95.5[micro]m x 43.5-48.0[micro]m respectively in the genus. Wall thickness varies from 1.5- 3.0[micro]m on the abaxial surface to 4.5-7.5[micro]m on the adaxial surface in the genus (Table 2).

[FIGURE 1 OMITTED]

In Portulaca, mean stomata distribution is not uniform on the two surfaces except in P. oleracea, mean distribution size however, varies from 5 on both surfaces of P. oleracea to 12 and 8 on the abaxial and adaxial surfaces of P. grandiflora respectively. Stomata size values range from 19.5-24[micro]m x 4.5-7.5[micro]m in P. grandiflora to 37.5-55.5[micro]m x 3.0-6.0[micro]m in P.oleracea on the abaxial surface and 15.0-21.0[micro]m x 6.0-9.0[micro]m in P.grandiflora to 30.0- 34.5[micro]m x 4.5-7.5[micro]m in P. quadrifida (Table 2). In P.grandiflora, cell number is almost uniform on both surfaces whereas it is more on the abaxial surface in P. oleracea than adaxial surface, but it is vice-versa in other species. Epidermal cells are longer and wider on the abaxial surface than adaxial surface in P. oleracea and P. quadrifida but reverse is the case in P. foliosa and P. grandiflora. Mean cell thickness is usually uniform on both surfaces in P. grandiflora and P. foliosa but it is opposite in other species (Table 2). Systematics relevance of epidermal characters have been documented and these characters have been used by workers to solve taxonomic problems both at the genus and species levels [Fontenelle, et al (1994), Kadiri and Ayodele (2003), Nyananyo and Olowokudejo, (1986), Ogundipe and Adegbite (1991), Ogundipe and Wujek (2004), Singh and Dube (1993)].

With these epidermal features the species of the two genera can be distinguished with the data revealing the existing affinities in the family. The correlations in the features studied have pointed to the inter relatedness of the taxa while the differences thus exhibited have shed light on the distinctness of the taxa. Stomatal character appears useful in distinguishing the genus Talinum, the size of the stomatal apparatus is usually greater on the adaxial surface than the other surface. In Portulaca as well, cell shape which is isodiametric on the adaxial surface is diagnostic of P. grandiflora.

Based on these foliar epidermal characteristics, Talinum cuneifolium can be distinguished from T. triangulare. Also, in Portulaca, P. foliosa and P. grandiflora are closer than P. oleracea and P. quadrifida and they can be distinguished as well (Tables 1 and 2). An indented dichotomous key presented below delimits the genera and the species of the family.
An Artificial Indented Dichotomous Key

1. Stomata size greater on the adaxial surface than
abaxial surface, cell shape usually irregular Talinum

2. Mean stomata number equal on both surfaces,
anticlinal wall undulate to curved triangulare

2. Mean stomata number not equal on either surface,
anticlinal wall usually curved

3. Mean cell length greater than 90.0[micro]m,
minimum cell number less than 8

3. Mean cell length not up to 90.0[micro]m, minimum
cell number 8 on both surfaces cuneifolium

1. Stomata size not always greater on the adaxial
surface, cell shape irregular to isodiametric Portulaca

4. Stomata number not more than 8, anticlinal
wall curved to undulate

5. Cell number not more than 6, wall thickness
uniform on both surfaces oleracea

5. Cell number up to 11, wall thicker on abaxial
surface than adaxial surface quadrifida

4. Stomata number up to 15, anticlinal wall curved
to straight-curved

6. Mean cell number not more than 15, cell size
range on the adaxial surface 100.5-123.0[micro]m
x 45.0-79.5[micro]m grandiflora

6. Mean cell number up to 24, cell size range on
the adaxial surface 67.5-90.0[micro]m x 42.0-60.0
[micro]m foliosa


REFERENCES

(1.) Dalziel, J. M. 1937. The Useful Plants of West Tropical Africa. Crown Agents for the Colonies. London. 612pp.

(2.) Evans, W. C. 1996. Trease and Evans' Pharmacognosy. W. B. Sanders Co. Ltd.,London: 612pp.

(3.) Fortenelle, G. B. , Costa C. G. and Machad , R. D. 1994. Foliar anatomy and micro- morphology of eleven species of Eugenia L. (Myrtaceae). Botanical Journal of the Linnean Society, 115: 111-133.

(4.) Heywood, V. H. (ed.). 1978. Flowering Plants of the World. Oxford University Press. Oxford : 336pp.

(5.) Hutchinson, J. and Dalziel, J. M. 1954. Flora of West Tropical Africa. v.1 Crown Agents for Overseas Governments and Administrations, London : 295pp.

(6.) Kadiri, A. B. and Ayodele, A. E. 2003. Comparative leaf micro-morphological characters of the Nigerian species of Rauvolfia Linn.(Apocynaceae). Bioscience Research Communications. 15: 6 :35-41.

(7.) Metcalfe, C. R. and Chalk, L. 1950. Anatomy of the Dicotyledons. Oxford University Press, Oxford. 724pp.

(8.) Metcalfe, C. R and Chalk, L. 1979. Anatomy of the Dicotyledons (2nd ed.). Vol. 1. Oxford University Press, Oxford: 276pp.

(9.) Nyananyo, B. L. and Olowokudejo, J. D. 1986. Taxonomic studies in the genus Talinum (Portulacaceae) in Nigeria. Willdenowia 15: 455-463.

(10.) Ogundipe, O. T. and Adegbite, E. A. 1991. The leaf epidermal studies of some species of Aspilia Thouars (Asteraceae). Feddes Repertorium 102 (7-8): 587-594.

(11.) Ogundipe, O. T. and Wujek, D. E. 2004. Foliar anatomy on twelve genera of Bignoniaceae (Lamiaceae). Acta Bot. Hung. 46: 290-312.

(12.) Singh, H. B. and Dube, V. P. 1993. Taxonomic significance of leaf epidermis in Corchorus Linn. (Tiliaceae) (1). Phytomorphology, 43 (3&4) :185-194.

A.B. Kadiri

University of Lagos, Department of Botany and Microbiology, Botany Research Laboratory,

Akoka yaba, Lagos, Nigeria Email:abkadiri2001@yahoo.com
Table 1: Qualitative Epidermal characters of the species of
Portulacaceae

Species Stomata type Cell shape Wall pattern

T. triangulare abaxial hemi, para irregular undulate
 adaxial hemi, para irregular curved
T. cuneifolium abaxial hemi, para irregular curved
 adaxial hemi para irregular curved
P. oleracea abaxial hemi, para irregular curved
 adaxial hemi, para irregular undulate
P. quadrifida abaxial para irregular undulate
 adaxial hemi, para irregular curved
P. foliosa abaxial para irregular curved
 adaxial hemi, para irregular curved
P. grandiflora abaxial para isodiametric, straight-
 irregular curved
 adaxial hemi, para isodiametric, straight-
 irregular curved

Species Wall thickness([micro]m)

T. triangulare abaxial 15.0 (3.0) 4.5
 adaxial 4.5 (6.0) 7.5
T. cuneifolium abaxial 1.5 (3.0) 4.5
 adaxial 3.0 (4.0) 4.5
P. oleracea abaxial 3 (3.5) 4.5
 adaxial (3.0)
P. quadrifida abaxial 6.0 (7.0) 7.5
 adaxial 4.5 (5.0) 6.0
P. foliosa abaxial 3.0 (3.5) 4.5
 adaxial 3.0 (3.5) 4.5
P. grandiflora abaxial
 3.0 (3.5) 4.5
 adaxial
 3.0 (3.5) 4.5

hemi = hemiparacytic, para = paracytic. Values in parenthesis are means
other values are minimum and maximum values.

Table 2: Quantitative epidermal characters of the species of
Portulacaceae

Species STOMATAL APPARAUTUS
 numbered width ([micro]m)
 lenght
 ([micro]m)
([micro])
T. triangulare (ab) 4 (5) 6 9.0 (13.0) 18.0
18.0(27.5)34.5
 (ad) 4(5)6 18.0(20.0)21.0
36.0(48.0)67.5
T.cuneifolium (ab) 10(13)16 18.0(20.5)24.0
15.0(20.5)24.0
 (ad) 2(4)6 25.5(26.5)27.0
33.0(43.5)57.0
P.oleracea (ab) 4(5)6 37.5(46.0)55.5
57.0(67.5)78.0
 (ad) 4(5)6 22.5(29.0)36.0
52.5(60.0)67.5
P. quadrifida (ab) 4(5)6 24.0(27.0)30.0
72.0(84.0)97.5
 (ad) 4(6)8 30.0(31.5)34.5
40.5(51.0)67.5
P. foliosa (ab) 10(12)15 24.0(26.0)27.0
39.0(42.0)45.0
 (ad) 6(7)8 21.0(23.5)25.5
42.0(53.0)60.0
P. grandiflora (ab) 9(12)15 19.5(21.5) 24.0
34.5(44.0)60.0
 (ad) 6(8)10 15.0(18.0)21.0
45.0(62.5)79.5

Species EPIDERMAL CELL
 numbered length width ([micro]m)
 ([micro]m)

([micro])
T. triangulare (ab) 3.0(4.5)6.0 5(7)9 82.5(89.5)96.0
18.0(27.5)34.5
 (ad) 3.0(4.0)5.0 8(9)10 70.5(82.5)102
36.0(48.0)67.5
T.cuneifolium (ab) 3.0(4.5)6.0 8(10)13 27.0(63.0)105
15.0(20.5)24.0
 (ad) 3.0(4.0)5.0 8(9)11 52.5(80.0)100.5
33.0(43.5)57.0
P.oleracea (ab) 3.0(4.5)6.0 4(5)6 23.0(163.0)225.0
57.0(67.5)78.0
 (ad) 3.0(7.0)15.0 3(4)5 96.0(137.0)165.0
52.5(60.0)67.5
P. quadrifida (ab) 3.0(4.5)6.0 8(9)11 20.0(147.0)180.0
72.0(84.0)97.5
 (ad) 4.5(6.0)7.5 3(5)6 29.0(134.5)147.0
40.5(51.0)67.5
P. foliosa (ab) 6.0(7.5)9.0 12(15)1 64.5(72.0)79.5
39.0(42.0)45.0
 (ad) 4.5(5.0)6.0 21(24)2 67.5(81.5)90.0
42.0(53.0)60.0
P. grandiflora (ab) 4.5(6.0)7.5 12(15)1 67.5(69.5)72.0
34.5(44.0)60.0
 (ad) 6.0(3.6)9.0 12(15)18 00.5(108.5)123.0
45.0(62.5)79.5

ad = adaxial ab = abaxial Values in parenthesis are means.

Table 3: List of taxa studied

Species Herbarium Collector Date of collection
 Number Name
T. cuneifolium
(Willd.) DC FHI 57093 M. G. Latilo 1. 8. 1967

T. triangulare
(Jacq.) Willd. LUH 25 A. B. Kadiri 8. x. 2004

Portulaca
oleracea Linn. LUH 32 A. B. Kadiri 7. viii. 2004

P.quadrifida
Hook LUH 35 A.B. Kadiri 18. ix. 2004

P. grandiflora FHI 59707 J. K. Morton 5. x. 1961

P.foliosa
Ker-Gawl FHI 65531 Z. O. Gbile 6. v. 1977

T. cuneifolium (Willd.) DC syn. T. portulacifolium (Forsk.) Asch. ex
Schweinf.)
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Author:Kadiri, A.B.
Publication:Bulletin of Pure & Applied Sciences-Botany
Date:Jan 1, 2006
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